Electricity Cost Calculator
Find what any appliance costs to run. Enter its power in watts, how long it runs, and your electricity rate — get the energy used in kWh and the cost per day, month and year.
How to use this calculator
- Enter the appliance's wattage (from its label) and hours used per day.
- Enter your electricity rate per kWh from a recent bill.
- Multiply up with quantity for multiple identical devices (e.g. light bulbs).
Formula used
A kilowatt-hour is 1,000 watts running for one hour — the unit your bill charges by. A 1,500 W heater for 1 hour uses 1.5 kWh. Watts ÷ 1000 converts to kilowatts before multiplying by hours.
Example calculation
A 1,500 W heater run 3 hours/day at 0.30/kWh: 1.5 kW × 3 h = 4.5 kWh/day → 1.35/day → ~493/year.
Left on 24/7 it would cost over 3,900 a year — which is why heating is where energy bills are won or lost.
Turning watts into money
Your electricity bill charges by the kilowatt-hour, but appliances are labelled in watts — so understanding running costs means converting between them. The formula is simple (watts ÷ 1000 × hours × rate), but the results are often surprising: high-wattage heating appliances (heaters, kettles, dryers, ovens) dominate bills, while low-wattage electronics cost little even when used constantly.
Two hidden costs are worth checking. Standby power — the few watts devices draw while "off" — runs 24/7 and quietly adds up across a house full of gadgets. And usage patterns matter more than ratings: a 2,000 W appliance used briefly can cost less than a 100 W device left on permanently. This calculator makes those comparisons concrete so you know where to focus.
Why use this calculator?
- See which appliances actually drive your bill — usually heating, not gadgets.
- Compare cost per day, month and year at a glance.
- Quantify standby power and always-on devices.
Frequently asked questions
How do I calculate the running cost of an appliance?
Multiply its power in kilowatts (watts ÷ 1000) by hours used and by your rate per kWh. A 2,000 W appliance for 2 hours at 0.30/kWh costs 2 × 2 × 0.30 = 1.20 per day.
What uses the most electricity at home?
Anything that makes heat: electric heaters, kettles, ovens, tumble dryers, immersion water heaters and air conditioning. These run at 1,500–3,000 W. Lighting and electronics are minor by comparison unless left on constantly.
Does standby power really cost much?
Individually little, but collectively yes — a house full of devices on standby can waste 5–10% of a bill. A device drawing 5 W on standby all year uses about 44 kWh — small per device, but it adds up across a home.